The present invention relates to applications of digital watermarking in conjunction with audio, video, imagery, and other media content.
Watermarking (or xe2x80x9cdigital watermarkingxe2x80x9d) is a quickly growing field of endeavor, with several different approaches. The present assignee""s work is reflected in U.S. Pat. No. 5,862,260; in copending application Ser. Nos. 09/503,881 and 09/452,023; and in published specifications WO 9953428 and WO0007356 (corresponding to U.S. Ser. Nos. 09/074,034 and 09/127,502). A great many other approaches are familiar to those skilled in the art. The artisan is presumed to be familiar with the full range of watermarking literature.
In the present disclosure it should be understood that references to watermarking encompass not only the assignee""s watermarking technology, but can likewise be practiced with any other watermarking technology.
The invention relates to methods, devices and systems for controlling operation of a device using a re-configurable watermark detector. In many applications, it is useful to be able to change the operation of a watermark detector. Such changes may include changing how the watermark detector decodes or interprets a watermark embedded in a signal of a given media type, such as audio, video or still images.
The ability to reconfigure a watermark detector is advantageous in many applications. When watermark detectors are deployed widely in consumer electronic devices and software, the capability to reconfigure the watermark detector reduces or prevents the devices and software from becoming obsolete when changes to the detector are needed. In content management schemes, where the watermark is used as a security feature, the security mechanism may be hacked. In other applications, the watermark technology provider may want to incorporate new features into the watermark detector, expand the message payload of the watermark, or change how the watermark payload is interpreted. In these circumstances, it is advantageous to be able to reconfigure a watermark detector, and particularly, to reconfigure the detector remotely.
One aspect of the invention is a method for controlling the operation of a device using a watermark. The method decodes a watermark embedded in a signal of a given media type, such as an image or audio signal (e.g., still images, motion pictures, audio, video, etc.). The watermark includes a command signal used to trigger a change in operation of the watermark detector. Based on the command signal, the method changes the operation of the watermark detector. This change may include changing how the watermark detector decodes or interprets a watermark in a signal of the media type. After changing operation of the watermark detector, the method decodes a usage control restriction from a watermark embedded in the signal.
The scope of this method encompasses a variety of implementations. The command signal may be represented as one or more bits of a watermark payload carried by the watermark. Changing the operation of the detector may include re-programming it or altering how it interprets watermark data embedded in a media object. For example, the method may transfer firmware instructions to the detector to replace instructions stored earlier. As another example, the command may change the operation of the detector according to a preprogrammed rule. The rule may define a change in watermark key, for instance. Yet another example is changing the operation of the detector by changing how a device responds to the watermark signal extracted from a media object. The behavior of a hardware or software media player, for instance, may be updated to respond differently to the watermark signal, and specifically, to the message carried in a watermark payload.
The method may use watermark payload data to change the operation of the detector. For example, the payload may specify instructions or watermark key data. In response to this payload data, the detector may install and execute new instructions or use the new watermark key to decode watermarks in media objects.
Another aspect of the invention is an alternative method for controlling the operation of a device using a watermark detector. This method receives a media object and a command associated with the media object signaling that the watermark detector requires an upgrade to decode a watermark from the media object. In response to the command, the method updates the watermark detector to create an updated watermark detector. It decodes the watermark from the media object with the updated watermark detector, including decoding a usage control restriction from the watermark. The command may be encoded in a watermark in the media object, or may be conveyed in a channel different than the watermark channel yet transmitted along with the media object (e.g., out-of-band channels like a file header or footer, sub-titling data channel, SCA channel, etc.). The scope of this method encompasses a variety of implementations. In addition, aspects of this method may be used in combination with aspects of the method summarized earlier.
Yet another aspect of the invention is a re-programmable watermark detector. The detector comprises a watermark decoder for detecting a command to upgrade the detector. It also includes instructions that are replaceable in response to detecting the command to upgrade the detector. The detector instructions are operable to decode a usage control restriction from a watermark and control playback or recording of a media object carrying the watermark. The instructions may be conveyed to the watermark detector along with a media object, either in a watermark payload, or a channel other than the watermark channel.
Another aspect of the invention is a method of an encoding an upgrade trigger in a watermark. The method receives a media object of a given media type, and encodes a watermark into the media object. The watermark includes a command signal used to trigger a change in operation of a watermark detector. When received in a detector, this change operates to alter how the watermark detector decodes or interprets a watermark in a signal of the media type. In addition, the method encodes a usage control restriction into the watermark, where the change in the operation of the detector enables the watermark detector to read the usage control restriction.
Further features and aspects of the invention will become apparent with reference to the following detailed description and accompanying drawings.